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<body>
<h1 id="css-">CSS清除浮动</h1>
<p><strong><code>overflow: hidden</code></strong></p>
<ol>
<li><code>overflow</code>溢出隐藏</li><li>清除浮动</li><li>解决<code>margin-top</code>的传递问题</li></ol>
<p><strong>（面试题）</strong>：</p>
<ul>
<li><p>单行文本出现省略号（4个必备条件，缺一不可）</p>
<ul>
<li><code>width</code> 宽度（不写宽度，默认继承父元素宽度）</li><li><code>overflow: hidden;</code>（溢出隐藏）</li><li><code>white-space: nowrap;</code></li><li><code>text-overflow: ellipsis;</code>文字隐藏的方式，以省略号的方式隐藏</li></ul>
</li><li><p>多行文本出现省略号（必备条件，主要应用在移动端）</p>
<ul>
<li><code>display: -webkit-box;</code> 弹性盒模型</li><li><code>-webkit-box-orient: vertical;</code>规定元素的排列方式：垂直排列</li><li><code>-webkit-line-clamp: 2;</code>：文字的行数（自定义）</li><li><code>overflow: hidden;</code>溢出隐藏</li></ul>
</li><li><p>多个元素在一行显示的方法</p>
<ul>
<li><code>display: inline;</code></li><li><code>display: inline-block;</code></li><li><code>float: left/right;</code></li></ul>
</li></ul>
<p><strong><code>display: inline-block;</code>元素的特点</strong></p>
<ul>
<li>盒子横向排列</li><li><code>verticle-align</code>属性会影响<code>inline-block</code>元素，值可能会设为<code>top</code></li><li>需要设置每一列的宽度</li><li><p>如果HTML源码中元素间有空格，列与列之间会产生空隙</p>
<ul>
<li><strong>解决方法</strong>：<ul>
<li>如果元素添加了<code>dispay: inline-block;</code>，父元素增加一个属性<code>font-size: 0;</code>，同时在元素本身增加<code>font-size</code>属性进行覆盖</li></ul>
</li></ul>
</li><li><p><code>display:inline-block;</code>在IE6/7下不兼容的解决方法</p>
<ul>
<li>增加<code>display: inline; zoom: 1;</code>属性</li></ul>
</li></ul>
<p><strong>IE7下块元素兼容<code>display: inline-block;</code></strong>写法？</p>
<ul>
<li>直接让块元素设置为内联对象（设置属性 <code>display: inline;</code>），然后触发块元素的<code>layout</code>（如：<code>zoom: 1;</code>等）。</li><li>兼容各浏览器的代码如下：<code>div {display: inline-block; *display: inline; *zoom: 1;}</code></li></ul>
<h1 id="-float-"><code>float</code>浮动</h1>
<p><strong><code>float</code>元素的特点</strong></p>
<ol>
<li>在一行显示</li><li>设置属性值为<code>left</code>时，浮动元素依次从父级盒子的左侧向右排列</li><li>自动具有块级元素的属性，不需要添加<code>display: block;</code></li><li>脱离文档流</li><li>子元素不会继承浮动属性</li><li>浮动元素下面的元素不能识别浮动元素的高度和位置，占据浮动元素的位置</li><li>所有的元素都可以使用浮动属性</li></ol>
<p><strong>文档流和脱离文档流</strong></p>
<ul>
<li>文档流：元素排版布局过程中，元素自动从左往右，从上往下的流式排列。</li><li>每个非浮动元素块级元素独占一行，浮动元素按规则浮在行的一端。当前行容量满则另起一行浮动。</li><li>内联元素不会独占一行</li><li>几乎所有元素（包括块级、内敛和列表元素）均可生成子行，用于摆放子元素</li><li>标准文档流等级：分为两个等级，块级元素和行内元素</li><li>脱离文档流：文档流内的正常元素识别不到这个元素（脱离文档流的元素相当于平行漂浮于文档流之上）</li></ul>
<p><strong><code>float</code>元素产生的影响</strong></p>
<ol>
<li>父元素设置背景颜色<code>background-color</code>不起作用</li><li>父元素设置内边距属性<code>padding</code>不会被撑开</li><li>父元素设置边框属性<code>border</code>不会被撑开</li></ol>
<h1 id="-float-">清除浮动<code>float</code></h1>
<p><strong>清除浮动的方法</strong></p>
<ol>
<li>给浮动元素的父级元素添加固定的高度<code>height</code>（不推荐）</li><li>给浮动元素的父级元素添加溢出隐藏属性<code>overflow: hidden;</code>；</li><li>给最后一个浮动元素后面添加一个块级元素，这个块级元素带有<code>clear: both;</code>属性<ul>
<li><code>clear</code>清除浮动元素对文档流内元素的影响（可以让文档流内的元素识别到浮动元素的高度）</li><li><code>left</code>清除<code>float</code>为<code>left</code>的影响</li><li><code>right</code>清除<code>float</code>为<code>right</code>的影响</li><li><code>both</code>清除<code>float</code>所有的影响</li><li><code>inherit</code>从父级元素上继承该属性值</li></ul>
</li><li><code>clearfix</code>清除浮动（固定代码）           <ul>
<li><strong>利用伪元素<code>:after</code>清除浮动必备条件，缺一不可</strong></li><li><code>display: block;</code>确保元素是一个块级元素</li><li><code>clear: both;</code>不允许左右两边有浮动对象</li><li><code>content: &#39;&#39;;</code>伪元素<code>:brfore/:after</code>自带的属性，如果不写，伪元素不起作用</li><li><strong>写全的样式属性；不是必备条件</strong></li><li><code>height: 0;</code> 防止在低版本浏览器中默认<code>height: 1px;</code>的情况，用<code>height: 0;</code>去覆盖</li><li><code>font-size: 0;</code> 字体大小 </li><li><code>overflow: hidden;</code> 溢出隐藏</li><li><code>visibility: hidden;</code> 让所有可见性的元素隐藏</li></ul>
</li></ol>
<p><strong><code>overflow: hidden;</code>和<code>visibility: hidden;</code>有什么区别？</strong></p>
<p><strong>（面试题）：如何让一个元素消失？</strong></p>
<ol>
<li><code>opacity: 0;</code>[0-1] 透明度</li><li><code>display: none;</code> 隐藏</li><li><code>widht/height/line-height + overflow</code>：宽/高/行高 + 溢出隐藏</li><li><code>visibility: hidden;</code>让所有可见性的元素隐藏 </li></ol>
<p><strong><code>clear: both;</code>的特点</strong></p>
<ol>
<li>元素需要是块级元素</li><li>元素不能带有浮动属性</li><li>元素必须放在最后一个浮动元素的后面</li></ol>

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